Network communication redundancy method

Abstract

There is provided an improved redundancy method for a communication network. The invention is based on the insight that a hitless failover can be performed by at the receiving node using a single common indexed play-out buffer in which a selective reconstruction of the transported data stream utilizing individual pieces, i.e. frames or packages, of a data stream received over multiple links is performed.

The invention claimed is: 
     
       1. A method for node to node communication comprising:
 providing each packet of a data stream to be transferred with a respective identifier, wherein the identifier corresponds to a relative position of a packet in said data stream; 
 transporting over at least two links replicated data of said data stream from a transmitting node to a receiving node; at said receiving node, 
 receiving and buffering packets from said at least two links for subsequent forwarding of said data stream; 
 wherein indentif said buffering includes reconstructing a predetermined portion of said data stream in a single common indexed buffer, based on received packets from at least one of said at least two links. 
 
     
     
       2. A method according to  claim 1 , wherein said step of reconstructing includes,
 selecting only one received packet with a specific identifier for writing to each indexed position of said buffer. 
 
     
     
       3. A method according to  claim 1 , further comprising:
 for each received packet,
 determining a corresponding buffer index, based on the identifier of said received packet; 
 checking if data has been written to the corresponding buffer index position, based on the determined buffer index, and 
 writing the received packet or a corresponding pointer to said received packet to its determined buffer index position, based on a determination that the data has not been written to the corresponding buffer index position. 
 
 
     
     
       4. A method according to  claim 2 , wherein simultaneous selection and writing to said buffer of received packets having different identifiers and being received on different links is supported. 
     
     
       5. A method according to  claim 2 , further comprising:
 for each received packet, setting a valid bit entry corresponding to a determined buffer index and link. 
 
     
     
       6. A method according to  claim 5 , further comprising:
 monitoring a current redundancy of said node to node communication based on said valid bit entries. 
 
     
     
       7. A method according to  claim 5 , further comprising:
 dropping any received packet arriving after a received packet with the same identifier is recorded. 
 
     
     
       8. A method according to  claim 1 , further comprising:
 at said receiving node and for each received packet,
 recording an inter-packet arrival time; 
 wherein said forwarding of said data stream is performed with an output rate, the output rate being determined based on recorded inter-packet arrival time data. 
 
 
     
     
       9. A method according to  claim 8 , wherein,
 said output rate is determined packet by packet, such that for a packet of a specific buffer index,
 the output rate is selected based on a recorded inter-packet arrival time of one of the received packets, the one of the received packets having an identifier corresponding to said specific buffer index. 
 
 
     
     
       10. A method according to  claim 8 , wherein the output rate when forwarding the data stream is selected based on recorded inter-packet arrival times from one of said at least two links. 
     
     
       11. A method according to  claim 1 , wherein forwarding of said data stream is initiated a predetermined time after a first packet of said data stream has been received on at least two links. 
     
     
       12. A method according to  claim 1 , wherein said method is used for hitless disconnection of an intermediary node arranged in one of said at least two links. 
     
     
       13. A non-transitory computer readable storage medium storing computer-readable instructions executable by a processor to cause the processor to perform the method according to  claim 1 . 
     
     
       14. A node in a communication system arranged for node to node communication over at least two links, the node comprising:
 a memory storing computer-readable instructions; and 
 a processor configured to execute the computer-readable instructions to,
 receive packets of a data stream, wherein each packet includes a respective identifier, and wherein said identifier corresponds to a relative position of a packet in said data stream; 
 buffer the packets of the data stream, wherein said buffering of packets includes reconstructing a predetermined portion of said data stream in a single common indexed buffer, using received packets from at least one of said at least two links; and 
 transport replicated data of said data stream over said at least two links to a receiving node.